A useful planning worksheet makes assumptions visible. Compare entered returns and distinguish today’s purchasing power from future nominal amounts; a deterministic result cannot make investment returns certain.
Keep contribution timing consistent
The scenario worksheet applies the annual nominal rate divided by 12 before adding each month-end contribution. Start-of-month contributions would earn another month of growth. All three scenarios use the same starting balance and contributions so you can inspect the effect of changing only the rate.
Translate a gap into a pot illustration
The target-pot tool subtracts other annual retirement income from desired annual spending, then divides the gap by your initial withdrawal-rate assumption. A 20,000 annual gap divided by 4% is 500,000. The rate is your assumption, not a guaranteed safe withdrawal rate.
Test what is omitted
Examine inflation, fees and different return scenarios separately. Fixed returns omit the order of good and bad years, changing spending and taxes. A target is an arithmetic starting point, not a certified personal retirement plan. Use actual product terms and appropriate personal advice for decisions beyond the model.
Worked example
Scroll the table horizontally on small screens to see every column.
| Annual gap | Rate assumption | Illustrative pot |
|---|---|---|
| 20,000 | 4% | 500,000 |
| 20,000 | 3% | 666,666.67 |
Neither assumption establishes how long a real portfolio will last.
Sources and checks
Examples are illustrative and can be checked with the linked tools. Read each tool’s assumptions before applying its result. How we verify methods.